An electronic safety device for vehicle occupants is described, for example, from article 1141 in the periodical Ingenieur de l'Automobile (1982) no. 6, pp. 69-77. Safety devices of this type must be constantly ready for operation to be able to protect the lives of vehicle occupants in the event of a serious accident. This constant operational readiness must be continually monitored by applying suitable test procedures encompassing as many component parts of the safety device as possible.
European Patent Application No. 0 284 728 describes a safety device for vehicle occupants which comprises a plurality of safety means for vehicle occupants, such as airbags, belt tighteners and/or the like, and a plurality of firing pellets for tripping each of these safety means. To limit the current flow through each of these firing pellets, which is made available from a limited energy reserve, a capacitor is connected in series to each firing pellet. This capacitor permits a current flow through the firing pellet only for as long as it is charged to the voltage level of the energy reserve.
An electronic safety device for vehicle occupants, which likewise has a capacitor connected in series to a firing pellet, is described by U.S. Pat. No. 5,146,104. However, this capacitor has such a small capacitance value that, given a maximum voltage, the charge it contains does not suffice to ignite the firing pellet. It requires, rather, a larger current to ignite the firing pellet, this current only being driven through the firing pellet by repeatedly charging and discharging, or recharging the capacitor connected in series to the firing pellet. A safety device of the last described type is particularly immune to unwanted spurious tripping, since a one-time current flow with the charge contained in the capacitor does not suffice to ignite the firing pellet. Moreover, a process that has already been introduced for igniting the firing pellet can be aborted when it turns out that the airbag does not have to be released after all, for example, due to a comparatively small risk of an accident.